(1) Field of the Invention
The present invention relates to a glass fiber reinforced polyolefin resin composition. More particularly, it relates to a glass fiber reinforced polyolefin resin composition which provides molded products substantially free from surface roughness and color shade and having excellent surface appearance and is superior in the balance of impact strength, stiffness, heat distortion temperature, surface hardness and moldability and thus is suitable as molding materials in the automotive fields, home electric appliance fields and other industrial fields.
(2) Description of the Related Art
For example, glass fiber reinforced polyolefin resins such as glass fiber reinforced polypropylene resins (GF-PP) are much superior to conventional polypropylene resins in mechanical properties such as tensile strength, stiffness and heat resistance and are comparable to so-called engineering plastics. Recently, their uses have been extended as materials for industrial parts such as automotive parts and electrical parts.
However, conventional glass fiber reinforced polyolefin resins such as GF-PP have the defects that surface roughness and color shade tend to occur due to orientation of glass fiber, resulting in deterioration of surface appearance of molded products, and thus have limited application to the fields where surface appearance is important such as use in home electric appliances, office automation apparatuses and interior automotive trims.
Hitherto, there have been proposed various methods to improve surface appearance of molded products made from GF-PP and, for example, a composition in which polystyrene and modified polymers are incorporated has been proposed (see Japanese Unexamined Patent Publication (Kokai) No. 58153/75).
However, when this composition is processed into a molded product, surface roughness and color shade is still not satisfactorily removed and further improvement has been desired.